Cubist Pharmaceuticals, Inc.,a biopharmaceutical company, has completed the acquisition of Optimer Pharmaceuticals, Inc. for an aggregate upfront cash consideration of approximately $551 million. Optimer stockholders approved the merger agreement at a special meeting of stockholders held on October 23, 2013.

Effective today, Optimer common stock will cease to be traded on the NASDAQ.

Cubist’s acquisition of Optimer follows the Company’s September 11, 2013 acquisition of Trius Therapeutics. Combined, Cubist expects the two acquisitions to add peak-year revenue of between $600 million and $1 billion and to be accretive to earnings in 2015.

“We are excited to complete this transaction and to welcome the Optimer team to Cubist,” said Michael Bonney, chief executive officer of Cubist. “Over the past few months, we have dramatically strengthened our commitment to global public health by bolstering our leadership in the research and development of antibiotics to treat serious and life-threatening pathogens. In doing this, our team has demonstrated the creativity and prudent risk-taking required to drive significant shareholder value in today’s highly dynamic healthcare environment.”

The completion of these two transactions will also help Cubist accelerate its focus on the research, development, and commercialization of products for patients in the acute care/ hospital setting. As part of this mission, Cubist will focus on driving its Building Blocks of Growth strategic goals through: a strong and growing commercial foundation and revenue base that the Company expects will deliver over $1 billion in 2013 revenue, driven by three marketed products: CUBICIN (daptomycin for injection), ENTEREG (alvimopan), and DIFICID (fidaxomicin); an exciting late stage pipeline, including tedizolid phosphate, for which the Company has submitted a New Drug Application with the US FDA, as well as ceftolozane/t azobactam, surotomycin, and bevenopran, all of which are in phase III clinical trials; and a growing, global commitment to public health through Cubist’s leadership in antibacterial R&D; Cubist hopes to deliver at least four of the Infectious Diseases Society of America’s goal of 10 new antibiotics by 2020.

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the research, development, and commercialization of pharmaceutical products that address significant unmet medical needs in the acute care environment.